Enhancing endogenous adenosine A2A receptor signaling induces slow-wave sleep without affecting body temperature and cardiovascular function.

Insomnia is one of the most common sleep problems with an estimated prevalence of 10%-15% in the general population. Although adenosine A2A receptor (A2AR) agonists strongly induce sleep, their cardiovascular effects preclude their use in treating sleep disorders. Enhancing endogenous A2AR signaling, however, may be an alternative strategy for treating insomnia, because adenosine levels in the brain accumulate during wakefulness. In the present study, we found that 3,4-difluoro-2-((2-fluoro-4-iodophenyl)amino)benzoic acid, denoted A2AR positive allosteric modulator (PAM)-1, enhanced adenosine signaling at the A2AR and induced slow wave sleep (SWS) without affecting body temperature in wild-type male mice after intraperitoneal administration, whereas the SWS-inducing effect of this benzoic acid derivative was abolished in A2AR KO mice. In contrast to the A2AR agonist CGS 21680, the A2AR PAM-1 did not affect blood pressure or heart rate. These findings indicate that enhancing A2AR signaling promotes SWS without cardiovascular effects. Therefore, small molecules that allosterically modulate A2ARs could help people with insomnia to fall asleep.

Cacao polyphenols ameliorate autoimmune myocarditis in mice.

Myocarditis is a clinically severe disease; however, no effective treatment has been established. The aim of this study was to determine whether cacao bean (Theobroma cacao) polyphenols ameliorate autoimmune myocarditis. We used an experimental autoimmune myocarditis (EAM) model in Balb/c mice. Mice with induced EAM were treated with a cacao polyphenol extract (CPE, n=12) or vehicle (n=12). On day 21, hearts were harvested and analyzed. Elevated heart weight to body weight and fibrotic area ratios as well as high cardiac cell infiltration were observed in the vehicle-treated EAM mice. However, these increases were significantly suppressed in the CPE-treated mice. Reverse transcriptase-PCR revealed that mRNA expressions of interleukin (Il)-1ß, Il-6, E-selectin, vascular cell adhesion molecule-1 and collagen type 1 were lower in the CPE group compared with the vehicle group. The mRNA expressions of nicotinamide adenine dinucleotide phosphate-oxidase (Nox)2 and Nox4 were increased in the vehicle-treated EAM hearts, although CPE treatment did not significantly suppress the transcription levels. However, compared with vehicle treatment of EAM hearts, CPE treatment significantly suppressed hydrogen peroxide concentrations. Cardiac myeloperoxidase activity, the intensity of dihydroethidium staining and the phosphorylation of nuclear factor-κB p65 were also lower in the CPE group compared with the vehicle group. Our data suggest that CPE ameliorates EAM in mice. CPE is a promising dietary supplement to suppress cardiovascular inflammation and oxidative stress.

Identification of a human cDNA sequence which encodes a novel membrane-associated protein containing a zinc metalloprotease motif.

We report the cloning and characterization of a human cDNA predicted to encode a novel hydrophobic protein containing four transmembrane domains and a zinc metalloprotease motif, HEXXH, between the third and fourth transmembrane domains, and have named the molecule metalloprotease-related protein-1 (MPRP-1). The MPRP-1 gene was localized to chromosome 1-p32.3 by radiation hybrid mapping, and Northern blot analysis revealed expression in many organs, with strong expression in the heart, skeletal muscle, kidney and liver. Immunohistochemical analyisis showed that MPRP-1 was localized in the endoplasmic reticulum (ER), and not in the Golgi compartment. Fragments of DNA encoding a segment homologous to the HEXXH motif of MPRP-1 are widely found in bacteria, yeast, plants, and animals. These results suggest that the MPRP-1 may have highly conserved functions, such as in intracellular proteolytic processing in the ER.

Selective cytotoxic mechanism of GTP-14564, a novel tyrosine kinase inhibitor in leukemia cells expressing a constitutively active Fms-like tyrosine kinase 3 (FLT3).

The receptor tyrosine kinase FLT3 is constitutively activated by an internal tandem duplication (ITD) mutation within the juxtamembrane domain in 20-30% of patients with acute myeloid leukemia. In this study, we identified GTP-14564 as a specific kinase inhibitor for ITD-FLT3 and investigated the molecular basis of its specificity. GTP-14564 inhibited the growth of interleukin-3-independent Ba/F3 expressing ITD-FLT3 at 1 microM, whereas a 30-fold higher concentration of GTP-14564 was required to inhibit FLT3 ligand-dependent growth of Ba/F3 expressing wild type FLT3 (wt-FLT3). However, this inhibitor suppressed the kinase activities of wt-FLT3 and ITD-FLT3 equally, suggesting that the signaling pathways for proliferation differ between wt-FLT3 and ITD-FLT3. Analysis of downstream targets of FLT3 using GTP-14564 revealed STAT5 activation to be essential for growth signaling of ITD-FLT3. In contrast, wt-FLT3 appeared to mainly use the MAPK pathway rather than the STAT5 pathway to transmit a proliferative signal. Further analysis demonstrated that the first two tyrosines in an ITD were critical for STAT5 activation and growth induction but that all of the tyrosines in the juxtamembrane region were dispensable in terms of the proliferation signals of wt-FLT3. These results indicate that an ITD mutation in FLT3 elicits an aberrant STAT5 activation that results in increased sensitivity to GTP-14564. Thus, FLT3-targeted inhibition is an attractive approach, with the potential for selective cytotoxicity, to the treatment of ITD-FLT3-positive acute myeloid leukemia.